Alidade



March 3-1, 1942. J. EDWIN ALIDAQE Filed July 1, 1940 2 Shets-Sheet 1 John Edwin March 31, 1942;

Filed July 1, 1940 J. EDWIN 2,277,965

ALIDAD'E Sheets-Sheet 2 'Fici l John Edwin Patented Mar. 31, 1942 s'ra'rs PATENT OFFICE ALIDADE John Edwin, Houston, Tex. Application July 1, 1940, Serial No. 343,320

3 Claims. (CI. 33-76) My invention relates to alidades and has for an object to provide an alidade by means of which maps may be easily and quickly drawn in the field.

Another object of the invention resides in providing an alidade requiring a minimum amount of effort on the part of the user in the use thereof.

An object of the invention resides in providing an alidade which greatly reduces the element of human error.

A still further object of the invention resides in providing an alidade having a blade provided with a pencil guiding edge and in providing pivot means acting between the board and blade for guiding the alidade about the axis thereof to positively locate the pencil guiding edge with reference to the axis of the pivot means.

A feature of the invention resides in arranging the pencil guiding edge in a plane passing through the axis of the pivot means.

Another object of the invention resides in providing a scale adjacent the guiding edge of the alidade blade and in disposing the axis of said pivot means at the zero line of the scale.

A still further object of the invention resides in making the scale detachable and in providing several scales interchangeable with one another to permit of drawing maps of different sizes.-

Another object of the invention resides in providing pivot means by means of which the alidade may be readily mounted or dismounted.

An object of the invention resides in providing pivot means by means of which the alidade may be readily pivoted at different localities with respect to the surface of the drawing board.

Another object of the invention resides in constructing the drawing board with a plurality of members to which the alidade may be pivoted whereby the pivot means may be applied at various positions on the drawing board.

A feature of the invention resides in constructing the alidade blade with a hole and in providing the drawing board with a stub shaft extending upwardly therefrom and adapted to enter the hole in the blade for pivoting the blade relative to the drawing board.

An object of the invention resides in detachably mounting the stub shaft on the board.

A still further object of the invention resides in constructing the board with a plurality of attaching members in the form of bushings situated at different localities about the surface thereof and at an elevation flush with or below the surface of the board so as to eliminate interference with the operation of the alidade, and in further providing a removable plug or member attached to the bushing and carrying the stub shaft.

A feature of the invention resides in screwing the plug into the bushing from below the drawing board.

A still further object of the invention resides in providing the plug with an eye or other means for attaching a plumb-bob and in constructing the eye so that the line of the plumb-bob is disposed in axial alignment with the axis of the stub shaft.

Other objects of the invention reside in the novel combination and arrangement of parts and in the details of construction hereinafter illustrated and/or described.

In the drawings:

Fig. 1 is an elevational view of an alidade illustrating an embodiment of my invention applied thereto.

Fig. 2 is a plan sectional view taken on line 22 of Fig. 1.

.Fig. 3 is a cross sectional View taken on line 3-3 of Fig. 2 and drawn to a greater scale.

Fig. 4 is a plan view of a drawing board and alidade showing the manner of using the alidade thereon.

Fig. 5 is a cross sectional view taken on line 5-5 of Fig. 4 and drawn to the same scale as Fig. 3.

For the purposeof illustrating my invention I have shown an alidade Which is indicated in its entirety by the reference numeral Ill. This alidade comprises a standard II which carries quadrants I2 by means of which a telescope I3 is adjustably supported. The device also includes a level M for leveling the instrument, and a level I 5 carried by the telescope for leveling the same. In addition, the necessary adjustments are provided which have not been shown in detail in the drawings. The telescope may be of the type provided with stadia hairs whereby distances from the reference point can be directly measured through the use of a stadia rod. The alidade It further includes a blade 24 which forms a feature of the instant invention.

The blade 2| is constructed from a strip of metal 22 which is shown in cross section in Fig. 3. The standard ll of the alidade is securely attached to the center of this blade by means of any suitable construction, not shown in the drawings. The blade 2| has the marginal portions 23 thereof formed with bevels 24. The under surface 25 of the blade 21 is smooth and fiat and is adapted to rest upon the surface of the drawing paper on which the alidade is to be used. At the ends of the blade 2| two finger pieces 26 are employed by means of which the alidade may be manipulated and moved about.

Overlying the bevels 24 of the blade 2| are two removable rulers 21 and 23. Since both of these rulers are similar in construction, only the ruler 21 will be described. Ruler 21 is constructed from thin sheet material such as metal, Celluloid, or the like and is provided with a body portion 29 overlying the upper surface of the blade 2|. Said ruler is further constructed with an angular portion 3|, which overlies the bevel 24. The outer edge 32 of the ruler 21 is constructed to form a pencil guiding edge along which a pencil may be run in drawing lines on the drawing board. The bent portion 3| of ruler 21 has enscribed in it suitable graduations 33 which extend up to the edge 32 and which form a scale, indicated in its entirety by the reference numeral 34, and by means of which the measurements taken on the plot to be mapped may be drawn to scale on the drawing paper. The ruler 21 is held attached to the blade 2| by means of a number of screws 35 which extend through slots 36 formed in the body portion 29 of the ruler and extending through the opposite edge 31 of the said ruler. When the screws are loosened the ruler may be quickly slid in place and when tightened the rulers become rigidly secured to the blade 2|. a sufficient distance apart to clear the finger pieces 26. Intermediate the ends of the same, said rulers are cut away as designated at 38 to clear the standard I At one end of the blade 2| is formed two ears 4| and 42 which extend outwardly beyond the pencil guiding edges 32 of the rulers 21 and 28. These ears are integral with the strip of metal 22 from which the blade is constructed and the two bevels 24 terminate at the said ears. The two rulers 21 and 28 hence extend only up to the said ears. In the ears 4| and 42 are drilled two holes 43 and 44 which constitute bearings and form part of a pivot means 45 for pivoting the alidade to the drawing board on which the alidade is to be used. The axes of the two holes 43 and 44 are situated at the zero points of the scales 34 of rulers 21 and 28 and are disposed in vertical planes containing the edges 32 of the said rulers. By means of this construction, a line drawn along the edge 32 of the ruler 21, if extended, would contain the axis of the hole 44 and measurements laid off in accordance with the scale 34 would commence at the axis of said hole.

In Fig. 4 I have shown a conventional form of drawing board which is designated by the reference numeral This drawing board may be constructed of wood or any other suitable material and is of suitable dimensions for making maps of the particular size desired. This drawing board may be supported on a tripod of any suitable design which, not forming a feature of the instant invention, has not been shown in the drawings. Preferably a tripod permitting of leveling up the drawing board is preferred whereby the board may be arranged in a horizontal plane at the plot where the map is to be made.

The bearing means 45 includes a plurality of attaching members or bushings 52, 53, 54, 55 and 56 which are mounted in the drawing board at suitable localities about the surface thereof. These bushings may be distributed about the The rulers 21 and 28 are situated ordinary alidade.

board at any of a number of localities which may be found desirable, and likewise the number of bushings employed may be varied to meet the requirements. -All of these bushings are similar in construction and use, and only the bushing 52 and associated parts will be described in detail. Bushing 52 is illustrated in cross section, in Fig. 5, and consists of a tubular portion 51 which extends through the drawing board 5| and lies flush with the uppermost surface 58 thereof. This bushing has a flange 59 recessed in the drawing board and is attached to the board by means of wood screws 6| which pass through the said flange and are screwed into the board proper. The flange 59 is flush with the underside of the board. The tubular portion 51 of bushing 52 has a bore 62 therein which is provided with threads 63 at the lower end. The bore 62 is accessible from the top of the drawing board and the threads 63 are accessible from the underside of the drawing board.

Cooperating with the bushing 52 is a threaded member or plug 64 which has a cylindrical portion 65 received within the bore 62 of bushing 52. This cylindrical portion has formed on the end of it a stub shaft 66 which, when the plug 64 is properly mounted, projects above the surface 58 of the drawing board and is adapted to be received in either of the holes 43 or 44 of the alidade blade 2|. The plug 64 also has a threaded portion 61 which screws into the threads 63 of the bushing 52 and by means of which the plug is held attached to the bushing. This portion has at its end a flange 68 which limits axial movement of the plug and serves to bring the stub shaft 66 in proper position to engage the alidade blade 2 Beneath the flange 68 is provided an eye 69 which is formed at the lowermost portion with a crotch 1|. The bight formed in the said crotch is situated at the axis of the stub shaft 66. The eye 69 is for the purpose of attaching a plumb-bob 12 to the drawing board 5|. This is accomplished by means of a line 13 which is attached to the plumb-bob 12 and which is also tied to the eye 69. The crotch 1| forms a guide portion which guides the line 13 into the desired position. When the plumbbob is properly mounted the line 13 lies in alignment with the axis of the stub shaft 66 so that the point of the plumb-bob is directly below the intersection of the axis 66 with the surface 58 of the drawing board 5|.

The use of the alidade is similar to that of an One of the bushings, 52 to 56 inclusive, is adopted for a starting point and the drawing board set up over the point on the plot which corresponds to the axis of said bushing and which will give the best lay-out of the map on the drawing board. The plug 64 is then screwed into the bushing 52 until the stub shaft 66 projects above the surface 58 of the drawing board the proper amount. The plumb-bob 12 is next attached to the eye 69 and the drawing board oriented and leveled to cause the surface 58 thereof to be level and to bring the plumb-bob 12 over the reference point on the plot. A sheet of drawing paper 50 is next punched at the desired locality to provide a hole in it adapted to slip over the stub shaft 66 of plug 64 and the paper securely attached to the board. The operator then applies the blade 2| of the alidade to the stub shaft 66 by bringing one or the other of the holes 33 or 34 into engagement with the said stub shaft. The user may employ either hole depending upon which of the two rulers 21 or 28 is to be used. In the drawings the alidade has been shown as used in conjunction with the ruler 21. The operator then proceeds in the customary manner. The telescope is leveled and sighted at the stadia rod which is held by the rod man at successive points to be plotted on the map. This is accomplished by swinging the alidade about the pivot means 45. By the readings on the rod the observer procures the distances of the points to be plotted from the reference point. The points to be plotted are transferred directly to the drawing paperfifl by placing the pencil at the edge 32 of the ruler 2'! at the proper graduation on the scale 34. The various points plotted may be connected as the survey proceeds until the completed map is drawn.

If desired, my improved device may be used for plotting points without the use of stadia hairs. In such case the distance between two or more particular bushings of the drawing board are measured by the scale 27 and are accurately laid out on the ground. The drawing board is then successively located over these points on the plot of ground and lined up with the other point. The operator then proceeds to sight the telescope to the various points to be plotted and draws lines along the edge 32 of the ruler 2'5 numbering the lines in accordance with numbers given to the points to be plotted. This the operator repeats for the various settings of the drawing board. The intersections of the corresponding lines thus give the points to be plotted which are connected up, as before.

In the use of my invention the user may rapidly take readings and plot the readings on the drawing board. Due to the pivoting of the alidade blade at the zero mark of the scale and along a line forming a continuation of the pencil guiding edge of the scale, it becomes unnecessary for the operator to manipulate the alidade on the drawing board further than swinging the same about the pivot means formed by the stub shaft of the invention. Also the readings may be directly plotted from the scale without particular skill on the part of the user. If desired, rulers having different scales may be attached to the blade of the alidade so that different maps may be drawn without the necessity of removing the rulers.

The advantages of my invention are manifest. The device is extremely simple and practical to use. The plumb-bob becomes accurately located below the reference points on the drawing board. The alidade is easily moved about and the only manipulation of the blade thereof required consists of swinging the same about its pivot. With my invention it becomes unnecessary to line up the pencil guiding edge of the alidade with points on the drawing and to thereafter use a separate scale and measure distances along the said line. With my invention the rulers may be easily interchanged so as to procure maps drawn to different scales. My improved alidade can be constructed at a nominal cost and without appreciable alteration of the alidade proper.

Changes in the specific form of my invention, as herein disclosed, may be made within the scope of what is claimed without departing from the spirit of my invention.

Having described my invention, what I claim as new and desire to protect by Letters Patent is:

1. In combination with a drawing board, an alidade including a blade adapted to rest upon the board and provided with a part having a pencil guiding edge, said blade having a cylindrical hole therein extending transversely to the plane of the drawing boardand being open on the underside of the blade, 2. bushing mounted in said drawing board and having a threaded hole therein, a threaded plug screwed into the hole of said bushing, a stub shaft on said plug extending upwardly beyond the surface of the drawing board and received within said hole, said hole forming a bearing cooperating with said stub shaft for rotatably guiding said blade for movement about the board.

2. In combination with a drawing board, an alidade including a blade adapted to rest upon the board and provided with a part having a pencil guiding edge, said blade having a cylindrical hole therein extending transversely to the plane of the drawing board and being open on the underside of the blade, an attaching member mounted in said drawing board and having a threaded hole therein, a threaded member screwed into the hole of said attaching member, a stub shaft on said threaded member extending upwardly beyond the surface of the drawing board and received within the hole of said blade, said hole forming a bearing cooperating with said stub shaft for rotatably guiding said blade for movement about the board, and means on said threaded member extending below the drawing board for supporting a plumb-bob.

3. In combination with a drawing board, an alidade including a blade adapted to rest upon the board and provided with a part having a pencil guiding edge, said blade having a cylindrical hole therein extending transversely to the plane of the drawing board and being open on the underside of the blade, an attaching member mounted in said drawing board and having a threaded hole therein, a threaded member screwed into the hole of said attaching member, a stub shaft on said threaded member extending upwardly beyond the surface of the drawing board and received within the hole of said blade, said hole forming a bearing cooperating with said stub shaft for rotatably guiding said blade for movement about the board, and an eye issuing from the underside of said threaded member for supporting a plumb-bob.

JOHN EDWIN. 

